MONTPELIER — Two of Vermont’s most powerful business groups are merging.

The Vermont Retail Association and the Vermont Grocers Association announced Wednesday that they would merge into a new entity — the Vermont Retail and Grocers Association.

Planning for the merger has been going on for more than a year. It was approved by the boards of both groups earlier this year and put to a membership vote Tuesday. Both memberships approved it.

“With the lines of retailing continuing to blur, it made sense for the VGA and VRA to examine options for the future,” said Tasha Wallis, executive director of the retailers group. “A single, larger organization will enhance advocacy efforts, improve member services and increase overall membership value for businesses.”

VGA President Jim Harrison, who has been with the group since 1987, will become the head of the merged association May 1. Wallis, who has been with the retailers group for six years, will step down April 30.

Wallis said she will look for another opportunity but has no job lined up.

“I haven’t figured out yet what that is, but I basically negotiated myself out of a job. It was the right thing to do,” she said.

A merger has been discussed sporadically for decades, Wallis said. Vermont’s small size is more conducive to one group, she said, and many other states already have one association that includes retailers and grocers.

Associations including the retailers and grocers groups have lost members as a result of health care reform. Wallis said many members joined for health insurance benefits that are no longer available.

“Some people were there for the particular benefits or services,” she said.

Wallis predicted some growing pains. She said the two groups “have evolved with slightly different cultures.” Both are political, but VGA members are typically more in lockstep with one another.

“I would say that today, VRA is more politically diverse. There have certainly been some issues where we haven’t taken a position because there has been such diversity,” Wallis said.

Harrison said the new group will hold even more political power.

“A merged organization will be a single clearinghouse of information and advocacy for retail-related issues, ranging from the sales tax to employment and business regulations. Policymakers will recognize the new association as an even stronger statewide voice for retailers and grocers,” he said.